The present invention relates to an apparatus for electro-erosive cutting with a cathode in the form of a wire, especially a round wire, that travels over at least two wire guides, and, second, a cathode in the form of a wire, especially a round wire, and, third a method of electro-erosive cutting using apparatus with a cathode in the form of a wire, especially a round wire.
Many types of apparatus for and methods of electro-erosive cutting are known. The basic apparatus usually comprises a stand with transmissions and wiring, a rinsing system, a generator, and numerical or computerized numerical controls. A cathode in the form of a wire cuts a blank out of the workpiece, which constitutes the anode, starting with an already drilled bore or reference point. Only round wires have been successfully employed until now.
A major objective in contemporary efforts to improve electro-erosive cutting is to increase profits by accelerating the cutting process. Efforts are almost exclusively devoted to transmitting more current through the wire, which requires a thicker wire and a sacrifice in precision.
Japanese Exposure 62-28122 (published Feb. 6, 1987) discloses using thicker wires with cross-sections that allow sharp corners to be cut. These wires can be square, triangular, or even flat in cross-section (FIG. 3). When they are used for cutting straight ahead, the cutting need no more be decelerated to attain as narrow a cut as possible than when a very narrow wire is employed. The limitations of these wires become evident, however, when it becomes necessary to cut around curves and angles in that the width of the cut will vary with the orientation of the wire along the cut. The cut will be narrowest only when an edge of the wire is facing directly forward. This situation, however, occurs only occasionally during a typical cut, as will be evident from the Japanese publication's FIG. 3. When a 90.degree. angle is cut with a flat wire for instance, the width of the cut will vary considerably upstream and downstream of the angle.